What is an MX-record (Mail eXchanger)?

An MX-record or Mail exchanger record is a type of resource record in the Domain Name System (DNS) specifying how e-mail should be routed using the Simple Mail Transfer Protocol (SMTP). Each MX record contains a priority and a host name (part that comes after the @), so that the collection of MX records for a given domain name points to the servers that should receive e-mail for that domain, and their priority relative to each other.

E.g.:
hostbasket.com MX 10 mail.hostbasket.com
hostbasket.com MX 50 backupmail.hostbasket.com

Important! The host name contained in an MX-record must have an A-record. CNAME-records or IP-addresses are prohibited in an MX record data. For mail.hostbasket.com and backupmail.hostbasket.com there has to be an A record.

Example of A-record:
Domain: fruit.com
Host name: mail
IP-address: 212.3.247.100 (this should be the IP-address of your mail server)

Now your mail server has the name mail.fruit.com which can be used in the MX-record.

Example of MX-record
Domain: fruit.com
Mail Exchanger: mail.fruit.com.
Priority: 10

All e-mail sent to name@fruit.com will be sent to the mail server mail.fruit.com with IP address 212.3.247.100.